The current invention relates to a device for at least intermittently generating an overpressure in a system in relation to an ambient pressure, with a pump that has a pressure side and an intake side, where during the generation of an overpressure, the pressure side is connected to the system and the intake side is connected to the ambient pressure by means of at least one first valve, in particular a solenoid valve, and the first valve throttles the intake volume flow due to its cross section. Furthermore, the current invention also relates to a valve, in particular an additional valve for the device according to the invention, with a valve inlet and a valve outlet that can be connected to each other.
Devices of this generic type include, for example, devices that are provided for connecting the pressure side or the intake side of a compressor or pump to a system by means of two solenoid valves in such a way that either an overpressure or a vacuum can be generated in the system. Known devices suitable for this are shown in FIGS. 1 and 2.
FIG. 1 shows a device that has a compressor or pump P with an intake side 10 and a pressure side 20. The pressure side 20 of the pump P is associated with a check valve R, which is connected by means of an output L2 to the pressure side 20 of the pump P. The device shown is provided for generating an overpressure or a vacuum in a system S. To this end, a first solenoid valve MV1 and a second solenoid valve MV2 are provided, by means of which the pump P can be connected to the system S in a suitable fashion. The first solenoid valve MV1 and the second solenoid valve MV2 are shown in their respective neutral positions. In this neutral position, the system S is connected to the ambient pressure by means of a line L7, the second solenoid valve MV2, a line L4, a line L5, the first solenoid valve MV1, and a line L8.
In order to generate an overpressure in the system S shown in FIG. 1, the second solenoid valve MV2 is switched. As a result, the system S is connected to the pressure side 20 of the pump P by means of the second solenoid valve MV2, the line L3, the check valve R, and the line L2. In the switched position of the second solenoid valve MV2, the line L4 is closed by the second solenoid valve MV2. The line L6 is likewise closed by the first solenoid valve MV1, which is in its neutral position. During overpressure operation, the intake side 10 of the pump P is connected to the ambient pressure U by means of a line L1, a line L5, the first solenoid valve MV1, and a line L8.
In order to generate a vacuum in the system S shown in FIG. 1, the first solenoid valve MV1 is switched out of the position shown in FIG. 1, while the second solenoid valve MV2 remains in the neutral position shown in FIG. 1. In this position of the first solenoid valve MV1, the line L5 is closed by the first solenoid valve MV1, while the line L6 is connected by the first solenoid valve MV1 to the line L8 and therefore to the ambient pressure. As a result, the pressure side 20 of the pump P is connected to the ambient pressure by means of the line L8, the first solenoid valve MV1, the line L6, the line L3, the check valve R, and the line L2. The system S is therefore connected to the intake side 10 of the pump P by means of the line L7, the second solenoid valve MV2, the line L4, and the line L1. As mentioned above, in the generic device according to FIG. 1, the system S is connected to the ambient pressure U when the first solenoid valve MV1 and the second solenoid valve MV2 are in their neutral positions.
By contrast, in the likewise known device according to FIG. 2, the system S is sealed when the solenoid valves are disposed in their neutral positions, as will be explained in detail below. The device according to FIG. 2 also has a pump P with an intake side 10 and a pressure side 20. The pump P is once again associated with a check valve R, which is connected by means of a line L12 to the pressure side 20 of the pump P. The system in which the overpressure or vacuum is to be generated is once again labeled with the reference letter S and the ambient pressure is once again labeled with the reference letter U. The device has a first solenoid valve MV1 and a second solenoid valve MV2, whose respective neutral positions are shown in FIG. 2. In these neutral positions, the line L17 is closed by the second solenoid valve MV2 while the line L15 is closed by the first solenoid valve MV1. As a result, the system S is sealed in the neutral position of the first solenoid valve MV1 and second solenoid valve MV2.
In order to generate an overpressure in the system S with the device according to FIG. 2, the second solenoid valve MV2 is switched, while the first solenoid valve MV1 remains in the neutral position shown in FIG. 2. When the second solenoid valve MV2 is switched, the system S is connected to the pressure side 20 of the pump P by means of the line L17, the second solenoid valve MV2, the line L13, the check valve R, and the line L12. The line L15 is closed by the first solenoid valve MV1 and line L14 is closed by the second solenoid valve MV2. During overpressure operation, the intake side 10 of the pump P is connected to the ambient pressure U by means of the line L11, the first solenoid valve MV1, and the line L16.
In order to generate a vacuum in the system S with the device according to FIG. 2, the first solenoid valve MV1 is switched out of the position shown in FIG. 2, while the second solenoid valve MV2 remains in its neutral position. As a result, the system S is connected to the intake side 10 of the pump P by means of a section of the line L17 that is closed by the second solenoid valve MV2, the line L15, the first solenoid valve MV1, and the line L11. During vacuum operation the pressure side 20 of the pump P is connected to the ambient pressure U by means of the line L12, the check valve R, the line L13, the second solenoid valve MV2, the line L14, and a section of the line L16 that is closed by the first solenoid valve MV1.
One disadvantage of the known devices shown in FIGS. 1 and 2 lies in the fact that the intake volume flow is throttled by the respective intake-side first solenoid valve MV1, as a result of which the compressor or the pump P achieves a lower pneumatic output. One obvious solution to this problem, namely to avoid the undesirable throttling of the intake volume flow by providing the intake-side solenoid valve with a sufficiently large cross section, entails other problems. A valve of this kind with a sufficiently large cross section requires large dimensions, is heavy, and is therefore expensive. Furthermore, in many cases it is desirable to use identical or similar valves on both the pressure side and the intake side.
Because the device according to the invention has means for providing an additional cross section for the intake volume flow during the generation of an overpressure, a higher pneumatic output can be achieved with the pump. Furthermore, the dimensions and weight of the first valve do not have to be increased and if a second valve is provided, identical or similar first and second valves are used.
A preferred embodiment of the device according to the invention provides that the means include at least one additional valve, which is connected in parallel to the first valve during the generation of an overpressure. As a result, the total cross section available for the intake volume flow can be increased by the cross section of the additional valve.
Particularly when the first valve is a solenoid valve, it is preferable that the additional valve be opened by an overpressure generated in the system. As a result, it is not necessary to provide additional energy sources for actuating the additional valve, but it is sufficient, for example, to connect a line leading to the system or the system itself to the additional valve in a suitable manner.
Preferably, the device according to the invention also includes the provision that if the pressure in the system decreases, then the additional valve is closed, preferably automatically, for example by means of the decreasing pressure itself.
In a preferred embodiment of the device according to the invention, a second valve, in particular a solenoid valve is provided; during the generation of the overpressure, the pressure side of the pump is connected to the system by means of the second valve.
Particularly in this instance, the device according to the invention can also be suitable for generating a vacuum in the system in relation to the ambient pressure. In this connection, the invention can include the provision that during the generation of the vacuum, the pressure side of the pump is connected to the ambient pressure by means of the first valve, while the intake side of the pump is connected to the system by means of the second valve. This can eliminate the disadvantages of the prior art mentioned at the beginning in conjunction with FIGS. 1 and 2.
Particular embodiments of the device according to the invention can include the provision that during the generation of an overpressure, the additional valve also functions as a pressure relief valve. This embodiment is particularly useful when the additional valve is connected to the system by means of a line and approximately the same pressure conditions as in the system prevail in at least a region of the additional valve.
The current invention also relates to a valve, in particular an additional valve for the device according to the invention, as has a ready been explained above. In this valve, the invention provides that the valve has a control pressure inlet, which is connected to a control chamber, and that the valve inlet is connected to the valve outlet when a predetermined pressure is exceeded in the control chamber. With regard to the device according to the invention, a valve of this kind can be actuated, for example, by the pressure prevailing in the system and as a result, during the generation of an overpressure, can provide an additional cross section for the intake volume flow without the need for additional energy sources to actuate the valve.
The valve according to the invention preferably includes the provision that the valve inlet is connected to the valve outlet by means of a spatial expansion of the control chamber.
To this end, the control chamber can be adjoined by a diaphragm, for example, which permits a spatial expansion of the control chamber. In this connection, the control chamber can be comprised, for example, by a housing that is open on one side; the open side of the control chamber is then adjoined by the diaphragm. Naturally, the housing can have suitable connections, for example in order to permit the control chamber to be connected to a system in which an overpressure is to be generated.
The valve according to the invention can also include the provision that on the side of the diaphragm oriented away from the control chamber, a valve chamber is provided, which is connected to a valve outlet, and the provision that the valve chamber is sealed off from the valve inlet in the neutral position of the diaphragm.
Particularly in this case, it can be advantageous if the valve chamber has a valve seat, which cooperates with a valve plate. The valve seat and the valve plate produce a reciprocal seal when the valve is closed.
In this connection, the invention can also include the provision that with a spatial expansion of the control chamber, the diaphragm acts on the valve plate in such a way that the valve chamber is connected to the valve inlet. As a rule, the valve plate is moved away from the valve seat for this purpose.
In this connection, the diaphragm can act on the valve plate, for example by means of a rod-shaped element.
The diaphragm and/or the rod-shaped element and/or the valve plate can be embodied of one piece with one another.
In addition, the diaphragm and/or the rod-shaped element and/or the valve plate can be comprised of a rubber-elastic material. Even in this embodiment, however, the rod-shaped element must be rigid enough to be able to transmit the required force from the diaphragm to the valve plate.
A preferred embodiment of the valve according to invention also includes the provision that when a maximal pressure in the control chamber is exceeded, the valve connects the control pressure inlet to the valve inlet and/or to the valve outlet. In this manner, the valve according to the invention can also function as a pressure relief valve.
To this end in particular, the invention can include the provision that a supporting plate acts on the diaphragm in order to seal off the control chamber from the valve chamber by means of the diaphragm as long as the maximal pressure in the control chamber is not exceeded.
In this connection, the supporting plate can be prestressed by a spring element, for example a spiral spring, in order to suitably act on the diaphragm. When the valve according to the invention is also functioning as a pressure relief valve, the spring force of a spring element of this kind can influence the maximal pressure at which the pressure relief valve opens.
In particular, in order to assure a sealing in relation to the valve inlet and/or the valve outlet in the neutral position of the valve, the invention can include the provision that a spring element prestresses the valve plate in the direction of the valve seat.